we don't know if focus will work on classic. So, as I understand, it will look like:
One master tank or healer doesn't matter must have multiple action bars one or two for himself and others for slaves, for example 1 acion bar for mage1, 1 action bar for mage2, lock, healer.

So 5 or 6 action bars with main spells of each party member to manage them from one master.